U.S. Pat. No. 7,132,581 concerns processes for converting oxygenates to olefins that include a step of pretreating catalyst used in the conversion reaction. A fresh or regenerated metalloaluminophosphate molecular sieve, which is low in carbon content, is pretreated with an aldehyde. The aldehyde forms a hydrocarbon co-catalyst within the pore structure of the molecular sieve, and the pretreated molecular sieve containing the co-catalyst is used to convert oxygenate to an olefin product.
U.S. Pat. No. 7,057,083 relates to processes for converting oxygenates to olefins that include a step of pretreating molecular sieve used in the conversion reaction with a C4-C7 olefin composition, which contains one or more C4-C7 olefins. Fresh or regenerated molecular sieve, which is low in carbon content, is contacted or pretreated with the olefin composition to form a hydrocarbon co-catalyst within the pore structure of the molecular sieve, and the pretreated molecular sieve containing the co-catalyst is used to convert oxygenate to a lighter olefin product.
U.S. Pat. No. 6,844,476 describes a method for converting heavy olefins present in a product stream exiting a first reaction zone into light olefins and carbonaceous deposits on a catalyst without separation of the heavy olefins from the product stream exiting the first reaction zone. The method comprises creating the product stream exiting the first reaction zone, the product stream exiting the first reaction zone comprising the heavy olefins, moving the product stream exiting the first reaction zone to a second reaction zone without separation of the heavy olefins from the product stream exiting the first reaction zone, and contacting the product stream exiting the first reaction zone with the catalyst under conditions effective to form the light olefins, the contacting causing the carbonaceous deposits to form on at least a portion of the catalyst.
US20060161035 describes the average propylene cycle yield of an oxygenate to propylene (OTP) process using a dual-function oxygenate conversion catalyst is substantially enhanced by the use of a combination of:
1) moving bed reactor technology in the catalytic OTP reaction step in lieu of the fixed bed technology of the prior art;
2) a separate heavy olefin interconversion step using moving bed technology and operating at an inlet temperature at least 15° C. higher than the maximum temperature utilized in the OTP reaction step;
3) C2 olefin recycle to the OTP reaction step; and
4) a catalyst on-stream cycle time of 700 hours or less. These provisions hold the build-up of coke deposits on the catalyst to a level which does not substantially degrade dual-function catalyst activity, oxygenate conversion and propylene selectivity, thereby enabling maintenance of average propylene cycle yield for each cycle near or at essentially start-of-cycle levels.
U.S. Pat. No. 5,914,433 relates to a process for the production of light olefins comprising olefins having from 2 to 4 carbon atoms per molecule from an oxygenate feedstock. The process comprises passing the oxygenate feedstock to an oxygenate conversion zone containing a metal aluminophosphate catalyst to produce a light olefin stream. A propylene stream and/or mixed butylene is fractionated from said light olefin stream and butylenes and heavies cracked to enhance the yield of ethylene and propylene products. This combination of light olefin product and butylene and heavies cracking in a riser cracking zone or a separate cracking zone provides flexibility to the process which overcomes the equilibrium limitations of the aluminophosphate catalyst. In addition, the invention provides the advantage of extended catalyst life and greater catalyst stability in the oxygenate conversion zone. In said process the effluent of the riser cracking zone or the separate cracking zone is sent to the oxygenate conversion zone.
It has now been discovered a more efficient process to make light olefins, in particular propylene from oxygenates. This invention relates to a process including three zones: a XTO reaction zone containing catalyst wherein “X” (e.g. oxygenates) are converted into mainly light olefins, an OC reaction zone containing substantially the same catalyst wherein heavier olefins and optionally ethylene are cracked into other light olefins and a zone wherein the catalyst used in the other two zones is regenerated (the catalyst regeneration zone also referred as the regeneration zone).